MRI appearance of the different meniscal ramp lesion types, with clinical and arthroscopic correlation

Overview of Meniscal Injuries

The menisci play a crucial role in knee stability, load distribution, and shock absorption. Their anatomical structure is linked to the way they perform. Meniscal injuries are common in both athletic and nonathletic populations, accounting for > 60% of all reported knee injuries, making them the most common type of knee injury resulting from acute trauma or degenerative changes. Meniscal tears typically result from a combination of axial loading and rotational force. The medial meniscus is the most affected. Tears can be classified based on their location, pattern, and stability, influencing treatment decisions. The three patterns are horizontal tear (simple or complex with a flap), vertical or longitudinal tear (simple, bucket-handle, or specific case meniscal ramp tear), and radial tear (simple, parrot beak, and specific case meniscal root tears). Some diagnostic pitfalls are anatomical variants, ligamentous or tendinous structures, or variations in signal or meniscal shape.

Association between injury-related factors and cartilage T2 relaxation time in the subacute phase in patients after anterior cruciate ligament injury

OBJECTIVE

To investigate associations between meniscal tear, bone marrow lesions (BMLs), and post-injury knee loading, with cartilage T2 relaxation times on knee magnetic resonance imaging (MRI) in the subacute phase following acute anterior cruciate ligament (ACL) injury.

DESIGN

We studied both knees of 128 patients with ACL injury. The presence of meniscal tears and BMLs was determined on subacute MRI (mean 29 days [SD 13] post injury), and post-injury knee loading was measured using an accelerometer. Manual cartilage segmentation and T2 relaxation time mapping of tibiofemoral cartilage were performed on both knees. We used multiple linear regression models adjusted for age, sex, body mass index, and time from injury to MRI to evaluate the association between exposures and cartilage T2 relaxation times in the ACL-injured knee between individuals. We also performed paired t-tests for comparisons with the individual's non-ACL injured contralateral knee free of the exposure of interest.

RESULTS

There was an association between ipsilateral meniscal tear and prolonged T2 relaxation time in the superficial cartilage of posterior tibia in both compartments (beta-coefficient medial: 2.88, [95% CI 1.16-4.61], beta-coefficient lateral: 1.88, [0.17-3.58]). Findings were confirmed in the paired analyses with contralateral knees (mean T2 difference 1.43, [0.33-2.53] and 2.10 [0.48-3.71] respectively). We found no essential associations for the other cartilage subregions or for BMLs and knee loading.

CONCLUSION

In the subacute phase after ACL injury, ipsilateral meniscal tear is associated with prolonged cartilage T2 relaxation time in the posterior tibia. This finding highlights the importance of meniscus function in the ACL-injured knee.

Editorial Commentary: Medial Meniscal Ramp Tears Require Comprehensive Evaluation and Treatment

Various classifications have been proposed for medial meniscal ramp tears, but none have been subjected to validation, reliability, or outcome analysis. A medial meniscal ramp tear is a peripheral detachment of the posterior horn of the meniscus due to either a tear of the meniscocapsular junction or the meniscotibial ligament, or both. Ramp tears are commonly found in association with anterior cruciate ligament rupture. The fascial expansion of the semimembranosus tendon is attached to the posterior horn of the medial meniscus; excessive anterior translation of the tibia stimulates the semimembranosus to contract, resulting in a ramp tear. Risk factors include deep and superficial medial collateral ligament injuries, steep medial tibial slope, flatter lateral tibial slope, varus alignment greater than 3°, posteromedial tibial bone contusion on magnetic resonance imaging (MRI), Segond fracture, and a chronic injury (3 months or more from injury). Untreated ramp lesions are associated with increased anterior knee laxity, which may increase the risk of anterior cruciate ligament graft failure. Diagnosis of a ramp tear is not always straightforward. MRI has only moderate sensitivity because the posterior capsule tightens in extension, reducing meniscocapsular separation. High-resolution MRI with the knee in flexion can improve accuracy. Nevertheless, the gold standard for diagnosis is arthroscopy. Unstable tears should be repaired, and as the meniscocapsular junction has good vascularity, some stable tears may heal after abrasion or trephination. A good classification system should characterize a problem, determine the best treatment, and predict the outcome. Classification systems also aid the consistent reporting and comparison of clinical data.

Is Trochlear Dysplasia Associated with a High Prevalence of Repaired Anterior Medial Portal Lesions in Anterior Cruciate Ligament-Deficient Knees?

Introduction  Meniscal tears, especially in the medial meniscus, are common in anterior cruciate ligament (ACL) injuries. Repaired anterior medial portal (RAMP) lesions, specific meniscal injuries associated with ACL ruptures, affect the peripheral attachment of the posterior horn of the medial meniscus. While the relationship between femoral trochlear morphology and ACL tears is established, its association with RAMP lesions remains unexplored. This study investigates the association between femoral trochlear morphology and RAMP lesions in ACL-deficient knees using magnetic resonance imaging (MRI) and evaluates MRI's accuracy against arthroscopy. Materials and Methods  This hospital-based, cross-sectional observational study was conducted in a tertiary care center over 18 months. It included 126 adult patients who underwent arthroscopic ACL reconstruction and had preoperative MRI. Variables included age, gender, body mass index, trauma nature, and various MRI parameters, including femoral trochlear morphology and presence of RAMP lesions. MRI findings were compared to arthroscopic findings to evaluate diagnostic accuracy. Results  RAMP lesions were detected in 21 participants (16.7%) via MRI and 28 participants (22.2%) via arthroscopy. MRI showed 71.4% sensitivity and 99.0% specificity for detecting RAMP lesions. No significant association was found between femoral trochlear morphology and RAMP lesions. However, medial tibial slope (TS) and posterior medial tibial bone edema (PMTBE) were significantly associated with RAMP lesions. The agreement between MRI and arthroscopy was high (Cohen's kappa = 0.773, p  < 0.001). Conclusion  This study found no significant association between femoral trochlear morphology and RAMP lesions in ACL-deficient knees. Instead, medial TS and PMTBE were significant predictors. MRI proved to have high specificity but moderate sensitivity compared to arthroscopy.

Medial Meniscal Ramp Tears in Patients With Anterior Cruciate Ligament Tears Undergoing Reconstruction: A Surgically Relevant Classification System Based on Tear Morphology

PURPOSE

To develop an anatomically and surgically relevant classification system for medial meniscal ramp tears from prospectively collected data from a consecutive series of patients undergoing anterior cruciate ligament reconstruction (ACLR) with ramp tears.

METHODS

A series of consecutive patients undergoing ACLR with medial meniscal ramp tears treated by 2 orthopaedic surgeons between June 2021 and May 2024 were included in this study. After arthroscopic confirmation of a medial meniscal ramp tear, the tear morphology and repair technique were noted using a ramp tear diagram, operative notes, and surgical photographs and/or videos. Tears were classified as partial or complete, stable or unstable, and superior or inferior, as well as based on whether they were in the capsule or within 3 mm of the meniscal rim.

RESULTS

A total of 115 patients with a mean age of 27.0 years (range, 13-52 years) were included and grouped into 5 distinct groups based on ramp tear morphology. Tear patterns were classified into partial stable tears (type 1; n = 8, 7.0%), partial unstable femoral-sided (meniscocapsular and superior meniscus) tears (type 2; n = 8, 7.0%), partial unstable tibial-sided (meniscotibial and inferior meniscus) tears (type 3; n = 31, 27.0%), complete separation tears (type 4; n = 46, 40.0%), and complex tears (type 5; n = 22, 19.1%).

CONCLUSIONS

This study shows that it was possible to establish a medial meniscal ramp tear classification system for patients undergoing ACLR based on anatomic and arthroscopic morphologic tear documentation. In this study, tears were grouped into 5 distinct groups: partial stable ramp tears (type 1), partial unstable superior ramp tears (type 2), partial unstable inferior ramp tears (type 3), complete separation ramp tears (type 4), and complex ramp tears (type 5).

CLINICAL RELEVANCE

Previous studies have highlighted the importance of the ramp attachment for stability and the prevention of anterior cruciate ligament graft failure. Our classification system is based on a prospectively collected patient population and incorporates assessment of the tear for stability to probing, identification of the location of the tear, and a surgically relevant tear progression. With the described classification system, we hope to optimize repair techniques and improve outcomes associated with different ramp tear types.

Anterior Cruciate Ligament-Injured Knees With Meniscal Ramp Lesions Manifest Greater Anteroposterior and Rotatory Instability Compared With Isolated Anterior Cruciate Ligament-Injured Knees

PURPOSE

To investigate the effects of ramp lesion (RL) and its repair on knee instability in patients with anterior cruciate ligament (ACL) injury by quantitatively assessing anteroposterior and rotational knee instability before and after ACL reconstruction.

METHODS

All primary double-bundle ACL reconstructions using hamstring autografts between 2016 and 2021 were evaluated retrospectively. Patients with RLs without other meniscal injuries were included in group R, whereas those with isolated ACL injuries constituted group C. RL was repaired using all-inside devices in all patients in group R. Knee instability, including the amount of anterior tibial translation (ATT), and the acceleration and external rotational angular velocity of the knee joint (ERAV) during the pivot-shift test were assessed at the time of surgery. The pivot-shift test grade was recorded.

RESULTS

A total of 73 patients were included in this study. Preoperatively, group R (n = 23) had significantly greater pivot-shift grades (P = .039), ATT (6.0 mm, group R; 4.5 mm, group C, P < .001), acceleration (6.8, 2.8; P = .037), and ERAV (3.9, 2.8; P = .001) than group C (n = 50). Intraoperatively, ATT (-1.0 mm, -1.0 mm; P < .001), acceleration (1.2, 1.1; P < .001), and ERAV (1.4, 1.2; P < .001) were significantly decreased compared with the preoperative values in both groups. No significant differences in these values were observed between groups R and C.

CONCLUSIONS

ACL-injured knees accompanied by RLs exhibited significantly greater anteroposterior and rotatory instability than knees with isolated ACL injuries; increased knee instability can be effectively addressed by performing RL repair in conjunction with ACL reconstruction. The quantitative assessments employed-specifically measuring ATT, acceleration, and ERAV during the pivot-shift test-have allowed us to delineate these aspects of knee instability with greater precision.

LEVEL OF EVIDENCE

Level Ⅲ, retrospective comparative study.

Medial meniscus ramp tears: State of the art

Medial meniscus ramp tears are tears of the posteromedial capsule or peripheral rim of the posteromedial meniscus that frequently occur with anterior cruciate ligament (ACL) tears. The incidence and prevalence of medial meniscus ramp tears has been increasing in the recent literature due to the increased understanding of the anatomy and diagnosis of these tears. When a patient presents with an ACL tear, a medial meniscus ramp tear should be suspected if the patient has a grade 3+ Lachman or pivot-shift exam, a vertical line of increased signal intensity in the posterior capsule or peripheral meniscus on magnetic resonance imaging (MRI), or posteromedial tibial plateau bone bruising on MRI. When a ramp tear is suspected, proper arthroscopic probing, including utilizing the transnotch view (or potentially an accessory posteromedial portal) or performing a medial collateral ligament trephination should be considered as part of the diagnostic workup. Once a tear is identified, a surgical repair depends on the location and stability of the tear and the surgeon's preference. The most frequently utilized techniques include the all-inside device, an all-inside suture hook, and an inside-out repair. Studies reporting on clinical outcomes for patients with ramp tears generally report no difference in outcomes compared to isolated ACL reconstruction patients. No consensus has been made on the best repair technique; however, it is generally accepted that repair is superior to leaving a ramp tear in situ as ramp tears have the potential to progress into bucket-handle tears. Further studies should work to establish a surgically and anatomically relevant classification system that clearly defines tear locations and stability to better study patient outcomes for those with a medial meniscus ramp tear. The purpose of this article is to review the anatomy, diagnosis, and treatment of medial meniscus ramp tears.

High prevalence of associated injuries in anterior cruciate ligament tears: A detailed magnetic resonance imaging analysis of 254 patients

OBJECTIVES

To evaluate the type and prevalence of associated injuries by using magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears.

METHODS

Data from the Natural Corollaries and Recovery after ACL injury multicenter longitudinal cohort study were analyzed. Between May 2016 and October 2018, patients aged between 15 and 40 years, who had experienced an ACL tear within the last 6 weeks and sought medical attention at one of seven healthcare clinics in Sweden, were invited to participate. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopedic knee surgeon and a musculoskeletal radiologist reviewed all the MRI scans. The following structures were assessed: posterior cruciate ligament (PCL), medial collateral ligament (MCL) complex, lateral collateral ligament (LCL), popliteus tendon, medial meniscus (MM), lateral meniscus (LM), and cartilage. In addition, the presence of bone bruising, impaction fractures in the lateral femoral condyle (LFC) or posterolateral tibia (PLT), and Segond fractures were also assessed.  RESULTS: A total of 254 patients (48.4% males) with a mean age of 25.4 ± 7.1 years were included. The prevalence of associated injuries was as follows: PCL (0.4%), MCL {41.3% [superficial MCL and deep MCL (dMCL) 16.5%; isolated dMCL 24.8%]}, LCL (2.4%), MM (57.4%), LM (25.2%), cartilage (15.0%), bone bruising (92.9%), impaction fracture in the LFC (45.7%) and PLT (4.7%), and Segond fracture (7.5%).

CONCLUSIONS

The prevalence of associated injuries in patients with ACL tears was high. The findings reported in this study may serve as a reference tool for orthopedic surgeons and radiologists in the diagnosis of associated injuries using MRI in patients with ACL tears.

Evaluation of the reliability and accuracy of MRI for the diagnosis of meniscal ramp lesions

BACKGROUND

Meniscal ramp lesions are a special type of meniscal injury that affects the periphery of the posterior horn of the medial meniscus and/or its meniscocapsular attachments, strongly associated with anterior cruciate ligament (ACL) tears. Due to their location, these lesions can be missed arthroscopically so it is essential to diagnose them on preoperative magnetic resonance imaging (MRI).

PURPOSE

To evaluate the accuracy of MRI in detecting meniscal ramp lesions in patients with ACL tears using arthroscopy as the reference standard.

MATERIAL AND METHODS

Two musculoskeletal radiologists, blinded to the surgical findings, retrospectively and independently evaluated 106 knee MRI scans for the presence of meniscal ramp lesions in non-consecutive patients who underwent arthroscopic ACL reconstruction between January 2019 and July 2022 by a single surgeon at one institution. Having arthroscopy as reference, the diagnostic sensitivity and specificity as well as the positive and negative predictive values (PPV/NPV) of the MRI scans were calculated. Cohen's kappa coefficient was used to test inter-observer reliability. A P value <0.05 was considered statistically significant.

RESULTS

In the study group of 106 patients (72 men, 34 women; mean age = 33.84 ±13.12 years), 76 had an arthroscopy-confirmed meniscal ramp lesion, while 30 did not. The sensitivity and specificity of MRI for the detection of meniscal ramp lesion were 88% and 87%, respectively. The PPV and NPV were 94% and 74%, respectively. Inter-rater reliability was excellent (k = 0915).

CONCLUSION

This study demonstrates that MRI can accurately detect meniscal ramp lesions.

Meniscal Ramp Injury Diagnosis

Objective : This study compared diagnostic methods for meniscal ramp injury (magnetic resonance imaging [MRI], arthrotomography, and arthroscopy) to determine the most sensitive and the agreement level between them. Method:  We studied 21 patients, all young athletes with suspected anterior cruciate ligament (ACL) injury after trauma for at least 3 months and no evidence or history of other osteoarticular injuries in the knee. The patients underwent MRI and arthrotomography. Following ACL injury confirmation, they underwent arthroscopy for ligament reconstruction and evaluation of the medial meniscus to confirm or exclude a ramp injury. McNemar's agreement test compared the diagnostic methods. We also assessed specificity and sensitivity using arthroscopy as the gold standard with a 95% confidence interval and p < 0.005. Result : The results were consistent with the literature. MRI had 73.3% sensitivity and 83.3% specificity, with 76.2% agreement with the gold standard. Arthrotomography sensitivity and specificity were 100% and 66.7%, respectively, with 90.5% agreement with arthroscopy. Conclusion : In our study, arthrotomography was the most sensitive diagnostic method and had the highest agreement with the gold standard. We recommend its consideration for diagnosing ACL injuries.

Approaching ramp lesions from the different world of posterior knee compartment: A review of evidence with a proposal of a new classification and treatment

Ramp lesions (RLs) are peripheral lesions that occur in the posterior part of the medial meniscus or where it attaches to the joint capsule. The classification of the medial meniscus RLs has been the focus of numerous studies and publications. This review provides an overview of RL's current classification and treatment options in anterior cruciate ligament deficient knees. The study also aims to present a more practical classification system for RLs to assist in treatment decision-making. For the first time, we also presented a new surgical treatment for incomplete inferior and double-complete RL based on the posterior knee arthroscopy that provides direct access to the posterior meniscal borders, enabling effective treatment and stronger biomechanical repair.

Level of Evidence

Level V.

The Incidence of Injuries to Ramp Semimembranosus Complex Lesions After ACL Injury: An MRI Study

Background

Medial meniscal ramp lesions have recently been an area of interest because of their recognized prevalence in association with anterior cruciate ligament (ACL) ruptures. Anatomically, the medial meniscal ramp is composed of the meniscocapsular ligament in continuity with the semimembranosus muscle and the meniscotibial ligament. Diagnosis of ramp semimembranosus complex (RSC) injuries remains challenging, and their prevalence is likely to be underestimated in comparison with ramp lesions.

Purpose

To determine the prevalence of RSC lesions after a complete ACL rupture.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A retrospective database analysis was performed. The cohort consisted of the first 100 patients with complete ACL rupture confirmed by magnetic resonance imaging (MRI) who underwent knee arthroscopy for ACL reconstruction in 2019. The semimembranosus lesions were identified using MRI by 2 independent radiologists specializing in musculoskeletal imaging. The ramp lesions were initially diagnosed using MRI and then confirmed during arthroscopy by an experienced knee surgeon. The magnitude of rotatory instability was recorded using the pivot-shift test. A multivariate analysis was used to determine the lesions associated with the semimembranosus complex.

Results

Of 100 patients, 53 showed lesions of the RSC; among them, 30 ramp lesions were confirmed after arthroscopic evaluation, and 40 semimembranosus lesions (23 without ramp lesion and 17 with ramp lesion) were found using MRI. A positive pivot shift was present in 57% of patients with combined RSC injury (P = .04) compared with 36% in patients without an RSC lesion.

Conclusion

Lesions of the RSC were found in more than half of ACL ruptures in this retrospective cohort. Rotational instability could be associated with combined ACL and RSC injury.

Identifying unstable ramp lesions using ultrasonography

BACKGROUND

Patients with suspected ramp lesions on magnetic resonance imaging (MRI) or ultrasonography (US) healed and showed no instability based on intraoperative arthroscopic findings. The purpose of this study was to assess the use of US in evaluating ramp lesions preoperatively and intraoperatively.

METHODS

Eighty-two knees that underwent anterior cruciate ligament (ACL) reconstruction between January 2022 and June 2023 were included to assess the ramp lesion complication rate and instability using arthroscopic findings. The detection rate of ramp lesions using US at the initial visit and preoperatively was also investigated. The test-retest reliability was assessed using the intraclass correlation coefficient and analyzed using two-way random effects and absolute agreement. The patients were divided into two groups based on the presence or absence of ramp lesions, and these data were compared using Student's t-test. Statistical significance was set at p < 0.05.

RESULTS

On ultrasound examination, 90.0% of the cases had a ramp lesion at the initial examination, of which 22.2% were poorly delineated on the day of surgery. In the cases where the ramp lesion was unstable at the time of surgery, it could be delineated using US. In the cases where the ramp lesion was stable, it was difficult to delineate the lesion using US.

CONCLUSIONS

Unstable ramp lesions complicating ACL injuries could be detected using US.

Meniscal ramp lesion classification systems: A systematic review

PURPOSE

To describe the proposed classification systems for meniscal ramp lesions (RLs) in the literature and evaluate their accuracy and reliability.

METHODS

A systematic search was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-analyses guidelines utilising PubMed, Embase and Cochrane Library databases. Level I-IV studies referencing RLs along with either an arthroscopic- or magnetic resonance imaging (MRI)-based classification system used to describe RL subtypes were included.

RESULTS

In total, 21 clinical studies were included. Twenty-seven (79%) of the included studies were published in 2020 or later. There were four main classification systems proposed within the literature (two arthroscopic-, two MRI-based), describing tear patterns, mediolateral extent, associated ligament disruption and stability of the lesion. The first classification was proposed in 2015 by Thaunat et al. and is referenced in 22 (64.7%) of the included studies. The application of the Thaunat et al. criteria to MRI showed variable sensitivity (31.70%-93.8%) and interobserver agreement (k = 0.55-0.80). The Greif et al. modification to the Thaunat et al. system was referenced in 32.4% of the included studies and had a substantial interobserver agreement (k = 0.8). Stability to probing and specific tear location were each used to classify RLs in 28.6% and 23.8% of the included clinical studies, respectively.

CONCLUSION

Although there has been a recent increase in the recognition and treatment of meniscal RLs, there is limited consistency in descriptive classifications used for this pathology. Current RL classification systems based on preoperative MRI have variable reliability, and arthroscopic examination remains the gold standard for diagnosis and classification.

LEVEL OF EVIDENCE

Level IV.

How to repair medial meniscal ramp lesions: A systematic review of surgical techniques

Purpose

to provide a comprehensive overview of all the surgical techniques published in the literature for repairing meniscal ramp lesions focusing on the technical aspects and the pros and cons of every procedure. Such lesions can be managed using various approaches, each of this with its specific advantages and disadvantages.

Methods

Pubmed Central, Scopus, and EMBASE databases were systematically reviewed according to the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines for studies on surgical techniques for repairing meniscal ramp lesions through May 2023. Overall, 32 articles matched the selection criteria and were included in the study.

Results

Debridement alone may be sufficient for small stable meniscal ramp lesions but, for tears in the menisco-capsular junction that affect the stability of the medial meniscus, it seems reasonable to repair it, even though the clinical results available in literature are contrasting. All-inside sutures through anterior portals seems to be an effective solution for meniscal ramp lesions with MTL tears. All-inside sutures through posteromedial portals are particularly useful for large meniscal ramp lesions, in which an inside-out suture can also be performed.

Conclusion

Meniscal ramp lesions can be managed using various approaches, each of this with its specific advantages and disadvantages. Further research is required to determine the optimal technique that can be considered as the gold standard and can provide the better results.

Level of Evidence

Level III, systematic review.

The meniscotibial ligament does exist: An anatomic and histological description

Purpose

To describe the anatomical and histological characteristics of the human MTL (meniscotibial ligament) that keeps the meniscus stable and are rarely discussed.

Study design

Descriptive laboratory study.

Methods

In total, six fresh-frozen adult cadaver knees were dissected, and the dissection protocol were designed by two experienced anatomy professors. The anatomical morphology of MTL was observed. The main anatomical specimens included meniscus, tibial plateau, MTL. The osteotome was used to excise the portion of the tibial plateau, which could obtain the complex including partial meniscus, MTL, and a tibial fragment. A histopathologic study was performed by two experienced pathologists.

Results

Macroscopically, the MTL could be divided into two parts: medial meniscotibial ligament (MMTL)and lateral meniscotibial ligament (LMTL). The MMTL is distributed continuously, whereas the LMTL is discontinuous on the tibial plateau. The average length from the tibial attachment of the LMTL to the articular surface was 19 ± 1.0mm (mean ± SD). The average length from the tibial attachment of the MMTL to the articular surface was 10 ± 1.2 mm (mean ± SD). Microscopy of the MTL showed that the MTL is a ligamentous tissue, composed of a network of oriented collagenous fibers.

Conclusions

In all knees, the MTL was inserted on the outer edge of the meniscus, attaching to the tibia below the level of articular cartilage, which was key to maintaining the rotational stability of knee and the meniscus in the physiological position on the tibial plateau. Histological analysis of this ligament demonstrated that the MTL is a veritable ligamentous structure, which is made up of collagen type I-expressing fibroblasts.

Clinical relevance

This article contributes to the understanding of the anatomical and histological characteristics of the MTL. It is beneficial to promote the development of relevant surgical techniques for the MTL lesion.

Evaluating the Diagnostic Performance of MRI for Identification of Meniscal Ramp Lesions in ACL-Deficient Knees: A Systematic Review and Meta-Analysis

BACKGROUND

Despite vigorous efforts to delineate the efficacy of magnetic resonance imaging (MRI) for the diagnosis of meniscal ramp lesions, there is still a great deal of uncertainty regarding its diagnostic performance. Therefore, we conducted a systematic review and meta-analysis to investigate the diagnostic performance of MRI for detecting ramp lesions in anterior cruciate ligament (ACL)-deficient knees.

METHODS

We performed a systematic search of MEDLINE via PubMed, Scopus, Web of Science, and Embase and included all articles, published before October 20, 2022, comparing the accuracy of MRI with that of arthroscopy as the gold standard for diagnosis of ramp lesions. We performed statistical analysis using Stata and Meta-DiSc software. Quality assessment of the included studies was performed using the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies-2) tool.

RESULTS

This meta-analysis evaluated 21 diagnostic performance comparisons from 19 original research articles (2,149 patients). The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic (SROC) curve for diagnosing a ramp lesion were 0.70 (95% confidence interval [Cl], 0.66 to 0.73), 0.88 (95% Cl, 0.86 to 0.89), 6.49 (95% Cl, 4.12 to 10.24), 0.36 (95% Cl, 0.28 to 0.46), 24.33 (95% Cl, 12.81 to 46.19), and 0.88, respectively. Meta-regression using different variables yielded the same results.

CONCLUSIONS

MRI exhibited a DOR of 24.33 and moderate sensitivity, specificity, and accuracy for diagnosing ramp lesions in ACL-deficient knees. However, arthroscopy using a standard anterolateral portal with intercondylar viewing is recommended to confirm a diagnosis of a ramp lesion.

LEVEL OF EVIDENCE

Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Investigation of the anatomic risk factors in acute anterior cruciate ligament ruptures to develop ramp lesions of the medial meniscus by quantitative MRI

OBJECTIVE

To investigate the anatomic risk factors of knee in patients with acute non-contact anterior cruciate ligament (aACL) ruptures to develop ramp lesions.

METHODS

A total of 202 subjects were retrospectively divided into three groups: (1) aACL ruptures combined with ramp lesions group (n = 76); (2) isolated ACL ruptures group (n = 56) and (3) normal controls group (n = 70). Quantitative morphological parameters on MRI were measured including: diameter of medial femoral condyle (MFC), anterior-posterior length and depth of medial tibial plateau (MTP AP length and depth), lateral posterior tibial slope (LPTS) and medial posterior tibial slope (MTPS), asymmetry of LPTS and MPTS (LMPTS), lateral meniscal slope (LMS), and medial meniscal slope (MMS).

RESULTS

The MTP AP length, MTP AP length/MFC diameter ratio, MTP depth, LPTS and the asymmetry of LMPTS showed significant differences among the three groups (p < 0.001). The risk factors associated with the ramp lesions including a longer MTP AP length (OR 1.17, 95% CI 1.00-1.44, p = 0.044), increased MTP depth (OR 1.91, 95% CI 1.22-3.00, p = 0.005) and lager ratio (OR 1.11, 95% CI 1.01-1.22, p = 0.036). The highest AUC was the MTP AP length/MFC diameter ratio (0.74; 95% CI, 0.66-0.82). The combination model increased higher accuracy (0.80; 95% CI, 0.72-0.88).

CONCLUSION

Several bony anatomic characteristics of the knee, especially the morphology of medial tibia plateau, are additional risk factors for aACL ruptures to develop ramp lesions.

CRITICAL RELEVANCE STATEMENT

Predictive anatomic risk factors of the knee for patients with acute non-contact anterior cruciate ligament (aACL) ruptures to develop ramp lesions, especially the morphology of medial tibia plateau, are detectable by MRI.

KEY POINTS

Ramp lesion development can complicate aACL ruptures and requires specific treatment. Longer AP length and increased MTP depth are risk factors for concurrent ramp lesions. Identification of ramp lesions allows for the most appropriate treatment.

Magnetic resonance imaging shows low sensitivity but good specificity in detecting ramp lesions in children and adolescents with ACL injury: A systematic review

IMPORTANCE

The diagnosis of ramp lesions can be problematic, even with arthroscopy, due to their extreme posteromedial position. Consequently, they have been colloquially referred to as the "hidden lesions" of the knee. Undiagnosed and untreated injuries in this knee region may be associated with ongoing dynamic rotational laxity of the knee after anterior cruciate ligament reconstruction and an increased risk of anterior cruciate ligament graft failure.

AIM

This study aimed to systematically review the literature to assess the sensitivity, specificity and accuracy of magnetic resonance imaging (MRI) for detecting ramp lesions in children and adolescents with anterior cruciate ligament (ACL)-deficient knees. It was hypothesized that MRI has poor sensitivity for identifying ramp lesions in children and adolescents.

EVIDENCE REVIEW

A systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following search terms were used in the title, abstract and keywords fields: "ramp" or "meniscus" AND "children" or "adolescents." The outcome data extracted from the studies were incidence of ramp in concomitant with ACL lesion, MRI sensitivity, specificity, accuracy and positive and negative predictive values (PPV and NPV).

FINDINGS

Of the 387 patients with ACL injury, 90 were reported to have ramp lesions (23.3%). The mean age at the time of diagnosis was 15.3 ​± ​0.81 years. The mean time from injury to MRI was 116.1 ​± ​113.5 days, while the mean time from injury to surgery was 172.6 ​± ​139.1 days. The MRI taken to detect ramp lesions in the paediatric population showed a pooled sensitivity of 50%, specificity of 75%, accuracy of 70%, PPV of 41% and NPV of 79%.

CONCLUSIONS AND RELEVANCE

The prevalence of ACL-associated ramp lesions in children and adolescents is similar to that in adult populations. Magnetic resonance imaging has low sensitivity but good specificity for assessing ramp lesions. In the presence of a posteromedial tibial bone bruise or a thin fluid signal separating the posterior horn of the medial meniscus and the posteromedial capsule a ramp lesion should always be suspected.

LEVEL OF EVIDENCE

Level IV.

STUDY REGISTRATION

PROSPERO -: CRD42023453895.

Posteromedial Corner Injuries of the Knee: Imaging Findings

The posteromedial corner (PMC) of the knee is an anatomical region formed by ligamentous structures (medial collateral ligament, posterior oblique ligament, oblique popliteal ligament), the semimembranosus tendon and its expansions, the posteromedial joint capsule, and the posterior horn of the medial meniscus. Injuries to the structures of the PMC frequently occur in acute knee trauma in association with other ligamentous or meniscal tears. The correct assessment of PMC injuries is crucial because the deficiency of these supporting structures can lead to anteromedial rotation instability or the failure of cruciate ligaments grafts. This article reviews the anatomy and biomechanics of the PMC to aid radiologists in identifying injuries potentially involving PMC components.

Reverse Ramp Lesion Repair in Patients With Meniscotibial Ligament Avulsion Injury: The Hidden AMRI

Lesions of the meniscocapsular junction and the meniscotibial ligament (MTL) of the posterior horn of the medial meniscus are common with knee ligamentous injuries and associated with residual rotational instability if left untreated. MTL avulsion from its tibial attachment has never been described among different types of meniscocapsular disruptions so far. Both diagnosis and treatment of such an injury can be challenging. This article describes a detailed technique and proposes an algorithm to appropriate management of this rare injury.

A New Entity of Ramp Lesion Combined with Posterior Root Tear of the Medial Meniscus: A Case Report

CASE

This report describes a new pattern of meniscal tear in an 18-year-old man after a knee sprain; he had undergone anterior cruciate ligament revision (ACL-R) 3 years earlier. He was diagnosed with an anterior cruciate ligament (ACL) graft rupture, a ramp lesion (Thaunat type 4), and a posterior root avulsion fracture of the medial meniscus (MM) (LaPrade type 5). He was treated successfully with an all-inside repair of the ramp lesion, a transtibial pull-out repair of the root tear, and ACL graft revision and anterolateral stabilization.

CONCLUSION

This specific meniscal injury pattern should be recognized and documented, potentially warranting consideration as a new addition to Thaunat and LaPrade classifications as type 6.

The Effect of Varying Sizes of Ramp Lesions in the ACL-Deficient and Reconstructed Knee: A Biomechanical Robotic Investigation

BACKGROUND

Conflicting evidence has been reported regarding the biomechanical relevance of ramp lesions (RLs) on knee kinematics. Furthermore, the influence of the defect size of the RLs on anterior tibial translation (ATT) and external rotation (ER) is currently unknown.

PURPOSE

To evaluate the influence of RL defect size on knee kinematics in anterior cruciate ligament (ACL) deficiency and after simulated ACL reconstruction (sACLR).

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight cadaveric knee specimens were tested in a 6 degrees of freedom robotic test setup. Force-controlled clinical laxity tests were performed with 200 N of axial compression in 0°, 30°, 60°, and 90° of flexion: 5 N·m internal rotation (IR)/ER torque, 134 N ATT force, and an anteromedial drawer test consisting of 134 N ATT force under 5 N·m ER torque. After determining the native knee kinematics, the ACL was cut at the tibial insertion, followed by a transosseous refixation to simulate a surgical repair or reconstruction (simulated ACL reconstruction; sACLR). An RL was sequentially created with a length of 1, 2, and 3 cm. Each state of the RL was evaluated in the ACL-deficient state and after sACLR.

RESULTS

In the ACL-deficient state, only an RL of 3 cm length resulted in a significant increase of ATT in 30° of flexion (mean difference 0.73 mm; 95% CI, 0.36-1.1 mm). After sACLR, an RL had no significant effect. When looking at ER, an RL significantly increased ER in full extension in the ACL-deficient state in 2 cm (mean difference 0.9°; 95% CI, 0.08°-1.74°) and 3 cm length (mean difference 1.9°; 95% CI, 0.57-3.25). Furthermore, a 3-cm RL significantly increased IR in 0° of flexion in the ACL-deficient state (mean difference 1.9°; 95% CI, 0.2°-3.6°). No effect of ramp lesions on rotation was found after sACLR.

CONCLUSION

RLs result in a small increase in ATT, ER, and IR in ACL-deficient knees at early flexion angles, but not after sACLR.

CLINICAL RELEVANCE

Small RLs did not change time-zero knee kinematics and may, therefore, be left untreated, especially when the ACL is reconstructed.

Influence of a posteromedial meniscocapsular injury on the knee anterior laxity. A cadaveric study

PURPOSE

The number of anterior cruciate ligament (ACL) injuries has considerably increased in the recent years, especially in young adults and adolescents. Associated meniscal tears increase anterior and rotary laxity. Posterior peripheral meniscocapsular tear of medial meniscus is also called ramp lesion. Prevalence of 9% to 17% in adults and up to 23% in pediatric population has been reported. The aim of this study was to determine anterior laxity of cadaveric ACL-deficient knees with several size of ramp lesions.

METHODS

Fresh cadaveric knees were explored. Major osteoarthritis and/or ACL and meniscal tears on arthroscopy were exclusion criteria. Mean age at death was 86 years old. Dynamic laximetry with GNRB® device was made in several conditions: Knee prior to any procedure, after arthroscopic exploration, after ACL section, and then after increasing sizes of ramp lesions up to 30 mm. Anteroposterior laxity was measured with 2 loading forces successively (134N and 200N).

RESULTS

After ACL section only, tibiofemoral joint anterior laxity was significantly increased. Mean increase was 156% regardless of the loading force. No statistical laxity difference was found between knees with ACL section only and knees with ACL and meniscal section for any size of ramp lesions. Increasing size of ramp lesion was not correlated with increasing of laxity.

CONCLUSION

We could not find a threshold size of ramp lesion which increases knee anterior laxity. We were not able to determine a threshold recommending a ramp lesion repair.

High Prevalence of Superficial and Deep Medial Collateral Ligament Injuries on Magnetic Resonance Imaging in Patients With Anterior Cruciate Ligament Tears

PURPOSE

To assess the prevalence of and factors associated with medial collateral ligament (MCL) complex injuries on magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears.

METHODS

Data were extracted from the Natural Corollaries and Recovery After ACL Injury (NACOX) multicenter longitudinal cohort study. Between May 2016 and October 2018, patients who presented to 1 of 7 health care clinics across Sweden with an ACL tear sustained no more than 6 weeks earlier and who were aged between 15 and 40 years at the time of injury were invited to participate. All the patients included in this study underwent MRI. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopaedic surgeon specializing in knee surgery and a musculoskeletal radiologist reviewed all MRI scans. Injuries to the superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament were identified. Stepwise forward multiple binary logistic regression analyses were used to evaluate patient characteristics (age, sex, body mass index, preinjury Tegner activity level, and activity at injury) and injuries on MRI (lateral meniscus [LM] injury, medial meniscus [MM] injury, pivot shift-type bone bruising, medial femoral condyle [MFC] bone bruising, and lateral femoral condyle [LFC] impaction) associated with the presence of MCL complex tears.

RESULTS

In total, 254 patients (48.4% male patients) with a mean age of 25.4 ± 7.1 years were included. The overall prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries was 16.5% (42 of 254) and 24.8% (63 of 254), respectively. No isolated sMCL injuries were found. Posterior oblique ligament injuries were found in 12 patients (4.7%) with MCL (sMCL and dMCL) injuries. An LM injury (odds ratio [OR], 3.94; 95% confidence interval [CI], 1.73-8.94; P = .001) and LFC impaction (OR, 2.37; 95% CI, 1.11-5.07; P = .02) increased the odds of having an MCL injury, whereas an MM injury (OR, 0.26; 95% CI, 0.12-0.59; P = .001) reduced the odds. Isolated dMCL injuries were significantly associated with MFC bone bruising (OR, 4.21; 95% CI, 1.92-9.25; P < .001) and LFC impaction (OR, 3.86; 95% CI, 1.99-7.49; P < .001).

CONCLUSIONS

The overall combined prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries in patients with ACL tears was high (16.5% + 24.8% = 41.3%). The presence of an LM injury and LFC impaction increased the odds of having an MCL injury, whereas the presence of an MM injury reduced the odds. MFC bone bruising and LFC impaction were associated with the presence of isolated dMCL injuries.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Case report: unusual posteromedial capsular lesion with posterior lateral meniscus root tear in two patients with constitutional genu recurvatum presenting after an acute ACL injury

Ramp lesions of the medial meniscus and posterior lateral meniscus root tears (LMPRT) can be present simultaneously in up to 8% of patients undergoing anterior cruciate ligament (ACL) reconstruction. The prevalence of these complex and highly unstable meniscal tears increases exponentially with the severity of the injury. The posteromedial capsule (PMC) has often been disregarded in the past when discussing ligamentous and meniscal injuries, but the recent interest in ramp lesions has drawn surgeons' attention to the posteromedial structures of the ACL injured knee. While the meniscocapsular junction is commonly repaired in unstable ramp lesions, in the current literature there is no report regarding proximal PMC lesions, be they in isolation or associated with complex meniscal injuries.We report here two cases of proximal posteromedial capsular lesions associated with medial meniscus instability and posterior lateral root tears after ACL injury. The first case involves a meniscus ramp lesion associated with a proximal PMC tear and a posteromedial fluid collection in the muscle plane on magnetic resonance in a 22-year-old male soccer player. The second case involves a 21-year-old female soccer player who presented with a PMC lesion after hyperextension/valgus knee injury. The capsular lesions were repaired to restore capsular tension and improve medial meniscus posterior horn stability.

Medial meniscal posterior horn tears and ramp lesions in pediatric patients: lessons learned

Meniscal injuries are increasingly reported in pediatric patients due to early sports participation and are commonly encountered during anterior cruciate ligament reconstruction. Preoperative identification of meniscal tears is crucial, particularly when involving the posteromedial meniscocapsular junction (ramp lesion). MRI plays an important role in detecting this particular type of meniscal injury. Consequently, pediatric radiologists should be aware of particular MRI findings related to ramp lesions including the presence of a medial meniscal tear, peripheral meniscal irregularity, meniscocapsular junctional fluid-like signal intensity, and capsular ligament tears. Thus, we illustrate the lessons we have learned from our institutional multidisciplinary arthroscopic-MR correlation conference for retrospectively identified posterior horn medial meniscal tears and ramp lesions.

Lateral-medial asymmetry of posterior tibial slope and small lateral tibial plateau articular surface depth are morphological factors of lateral meniscus posterior root tears in ACL-injured patients

PURPOSE

To investigate whether knee morphological features, patient characteristics, and intraoperative findings are associated with a lateral meniscus (LM) posterior root tear (LMPRT) in anterior cruciate ligament (ACL) injuries with the integrated data from two academic centres.

METHODS

This retrospective study used registry data acquired prospectively at two academic centres. Patients with ACL reconstruction (ACLR) with LMPRT and no other LM injury were selected (LMPRT group) from each database. The control group included patients who underwent ACLR without LM tears. Patients were matched to the LMPRT group according to age and gender (1:1). Morphological factors evaluated on preoperative magnetic resonance image scans included lateral femoral condyle (LFC) anterior-posterior diameter, height, and depth; lateral tibial plateau (LTP) articular surface (AS) depth and sagittal plane depth; and lateral and medial posterior tibial slopes (PTSs). LFC height and depth ratios, LTP AS depth and sagittal plane depth ratios, and lateral-to-medial slope asymmetry were computed from previous measurements. Patient characteristics and intraoperative findings were extracted and compared between both groups.

RESULTS

The study included 252 patients (126 in each group). The lateral-medial asymmetry of PTS was greater in the LMPRT group (1.2° vs 0.3°, p < 0.05), and the LTP AS depth was smaller in the LMPRT group (31.4 mm vs 33.2 mm, p < 0.01). There were no differences in LFC morphology between the control and LMPRT groups. Pivot shift grade (p < 0.05), percentage of complete ACL tears (p < 0.05), and medial meniscus ramp lesions (p < 0.05) were significantly higher in the LMPRT group.

CONCLUSION

LMPRT was associated with significantly increased lateral-medial asymmetry of PTS and significantly smaller LTP AS depth. LMPRT was also associated with an increase in the preoperative pivot shift grade and the presence of a medial meniscus ramp lesion. These morphological characteristics are rather simple to measure and would serve as helpful indicators to preoperatively detect LMPRT, which is frequently challenging to diagnose preoperatively.

LEVEL OF EVIDENCE

Level III.

Greater Knee Rotatory Instability After Posterior Meniscocapsular Injury Versus Anterolateral Ligament Injury: A Proposed Mechanism of High-Grade Pivot Shift

Background

For anterolateral rotatory instability as a result of secondary soft tissue injuries in anterior cruciate ligament (ACL)-deficient knees, there is increasing interest in secondary stabilizers to prevent internal rotation (IR) of the tibia.

Purpose

To determine which secondary stabilizer is more important in anterolateral rotatory instability in ACL-deficient knees.

Study Design

Controlled laboratory study.

Methods

The lower extremities of 10 fresh-frozen cadavers (20 extremities) without anterior-posterior or rotational instability were included. Matched-pair randomization was performed, with each side per specimen assigned to 1 of 2 groups. In group 1, the ACL was sectioned, followed by the anterolateral ligament (ALL); in group 2, the ACL was sectioned, followed by sequential sectioning of the posterolateral meniscocapsular complex (PLMCC) and posteromedial meniscocapsular complex (PMMCC). The primary outcome was the change in relative tibial IR during a simulated pivot-shift test with 5 N·m of IR torque and 8.9 N of valgus force. The secondary outcomes were the International Knee Documentation Committee grade in the pivot-shift test and the incidence of the grade 3 pivot shift.

Results

In group 1, compared with baseline, the change in relative tibial IR at 0° of knee flexion was 1.4° (95% CI, -0.1° to 2.9°; P = .052) after ALL release. In group 2, it was 2.5° (95% CI, 0.4° to 4.8°; P = .007) after PLMCC release and 4.1° (95% CI, 0.5° to 7.8°; P = .017) after combined PLMCC and PMMCC release. Combined PLMCC and PMMCC release resulted in greater change of tibial IR with statistical significance at 0°, 15°, and 30° of knee flexion (P = .008, .057, and .004, respectively) compared with ALL release. The incidence of grade 3 pivot shifts was 10% in group 1 and 90% in group 2.

Conclusion

Posterior meniscocapsular laxity caused an increase in relative tibial IR as much as ALL injury in ACL-deficient knees in our simulated laboratory test, and greater anterolateral rotatory instability occurred with posterior meniscocapsular injury compared with ALL injury.

Clinical Relevance

Repair of the injured posterior meniscocapsular complex may be an important treatment option for reducing anterolateral rotatory instability in the ACL-deficient knee.

Ramp lesion in anterior cruciate ligament injury: a review of the anatomy, biomechanics, epidemiology, and diagnosis

Ramp lesions, commonly observed in patients with anterior cruciate ligament (ACL) injuries, have been previously defined as longitudinal tears around the meniscocapsular junction. However, the definitions and interpretations of ramp lesions have varied, emphasizing the need to confirm their presence before surgery and the importance of direct visualization using arthroscopy. Recent histological studies have reported new findings on ramp lesions, shedding light on their attachment mechanisms. The anatomical structures around the ramp lesion, such as the posterior horn of medial meniscus (PHMM), semimembranosus (SM), posteromedial (PM) capsule, and meniscotibial ligament (MTL), were assessed regarding how these structures could be attached to each other. The studies of ramp lesions have also contributed to the progression of biomechanical studies explaining the cause and effects of ramp lesions. Ramp lesion has been proven to stabilize the anteroposterior (AP) instability of ACL. In addition, various laboratory studies have demonstrated the relationship between rotational instability of the knee joint and ramp lesions. The analysis of risk factors of ramp lesion helped to understand the injury mechanism of the lesion. Many authors have evaluated the prevalence of ramp lesions in patients with ACL injuries. The development of arthroscopy techniques has influenced the outcomes of ACL reconstruction with the easy detection of ramp lesions. This review article aims to analyze the past findings and recent advancements in anatomical, biomechanical, and epidemiological studies of ramp lesions in patients who underwent ACL reconstruction, and provide various perspectives ramp lesions in patients with ACL reconstruction.

Frequency of anterolateral ligament tears and ramp lesions in patients with anterior cruciate ligament tears and associated injuries indicative for these lesions-a retrospective MRI analysis

OBJECTIVES

To assess the frequency of anterolateral ligament (ALL) tears and ramp lesions (RL) detected with MRI in patients with anterior cruciate ligament (ACL) tears and to describe associated injuries indicative for these lesions.

METHODS

In this retrospective study, 164 patients with surgically verified ACL tears were included. Preoperative MRI scans were reviewed for ALL tears and different types of RL. All coexisting meniscal tears, tears of the medial (MCL) and lateral collateral band (LCL), and posterior-medial tibial bone marrow edema (BME) were recorded. The frequency of ALL tears and RL was assessed and coexisting injuries were correlated using Pearson's chi-square test. A p < 0.05 was defined as statistically significant. In cases of multiple testing, Bonferroni's correction was applied.

RESULTS

ALL tears and RL combined were detected in 28 patients (17.1%), ALL tears in 48 patients (29.3%), and RL in 54 patients (32.9%) which were significantly associated to each other. ALL tears were significantly associated with tears of the posterior horn of the lateral meniscus (PHLM), BME, and with tears of the LCL and MCL. RL were significantly associated with tears of the posterior horn of the medial (PHMM) and PHLM, with BME, and with tears of the LCL.

CONCLUSIONS

ACL tears are associated with RL or ALL tears in about one-third of cases and with both lesions combined in about one-fifth of cases. ALL tears and RL are significantly associated with additional posttraumatic injuries, which can thus be indicative of these lesions.

KEY POINTS

• ACL tears were associated with ramp lesions or ALL tears in about one-third of the cases. • Ramp lesions and ALL tears were significantly associated with each other, tear in the PHLM, tear in the LCL, and BME. • ALL tears were more frequently associated with instable classified ramp lesion type 4b and type 5.

Visual Cascaded-Progressive Convolutional Neural Network (C-PCNN) for Diagnosis of Meniscus Injury

OBJECTIVE

The objective of this study is to develop a novel automatic convolutional neural network (CNN) that aids in the diagnosis of meniscus injury, while enabling the visualization of lesion characteristics. This will improve the accuracy and reduce diagnosis times.

METHODS

We presented a cascaded-progressive convolutional neural network (C-PCNN) method for diagnosing meniscus injuries using magnetic resonance imaging (MRI). A total of 1396 images collected in the hospital were used for training and testing. The method used for training and testing was 5-fold cross validation. Using intraoperative arthroscopic diagnosis and MRI diagnosis as criteria, the C-PCNN was evaluated based on accuracy, sensitivity, specificity, receiver operating characteristic (ROC), and evaluation performance. At the same time, the diagnostic accuracy of doctors with the assistance of cascade- progressive convolutional neural networks was evaluated. The diagnostic accuracy of a C-PCNN assistant with an attending doctor and chief doctor was compared to evaluate the clinical significance.

RESULTS

C-PCNN showed 85.6% accuracy in diagnosing and identifying anterior horn injury, and 92% accuracy in diagnosing and identifying posterior horn injury. The average accuracy of C-PCNN was 89.8%, AUC = 0.86. The diagnosis accuracy of the attending physician with the aid of the C-PCNN was comparable to that of the chief physician.

CONCLUSION

The C-PCNN-based MRI technique for diagnosing knee meniscus injuries has significant practical value in clinical practice. With a high rate of accuracy, clinical auxiliary physicians can increase the speed and accuracy of diagnosis and decrease the number of incorrect diagnoses.

MR Imaging of Acute Knee Injuries: Systematic Evaluation and Reporting

Acute knee injury ranges among the most common joint injuries in professional and recreational athletes. Radiographs can detect joint effusion, fractures, deformities, and malalignment; however, MR imaging is most accurate for radiographically occult fractures, chondral injury, and soft tissue injuries. Using a structured checklist approach for systematic MR imaging evaluation and reporting, this article reviews the MR imaging appearances of the spectrum of traumatic knee injuries, including osteochondral injuries, cruciate ligament tears, meniscus tears and ramp lesions, anterolateral complex and collateral ligament injuries, patellofemoral translation, extensor mechanism tears, and nerve and vascular injuries.

Reproducibility of MRI in the diagnosis of meniscal ramp lesions: an inter-observer study

BACKGROUND

Meniscal ramp lesions have gained much prominence in recent years due to a significant increase in their diagnosis and their important biomechanical involvement in the knee. A new proposed classification of these lesions has recently been published.

PURPOSE

To evaluate the reproducibility of the new classification of meniscal ramp lesions recently published using magnetic resonance imaging (MRI).

MATERIAL AND METHODS

A total of 249 post-traumatic knee MRI studies were evaluated by three musculoskeletal radiologists independently. Patients with an anterior cruciate ligament (ACL) tear on MRI in addition to a recent history of trauma to the knee for <12 months were included in the study, for a total of 95. We carried out an inter-observer concordance study to analyze whether the new classification is reproducible to detect meniscal ramp lesions and to classify them into their different types.

RESULTS

Among our study cohort of 95 patients, we found 47 (49.5%) ramp lesions. In the inter-observer study, we obtained a good concordance (k = 0.733) in the detection of these lesions and an excellent one (k = 0.843) when the type of lesion is described.

CONCLUSION

This study demonstrates that the new classification of meniscal ramp lesions has good reproducibility on MRI.

High prevalence of meniscal ramp lesions in anterior cruciate ligament injuries

PURPOSE

To evaluate the prevalence of and factors associated with meniscal ramp lesions on magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) injuries.

METHODS

Data from the Natural Corollaries and Recovery after ACL injury multicentre longitudinal cohort study (NACOX) were analysed. Only patients who underwent MRI were included in this study. All MRI scans were reviewed by an orthopaedic knee surgeon and a musculoskeletal radiologist. The patients were divided into two groups, those with and without ramp lesions according to MRI findings. Univariable and stepwise forward multiple logistic regression analyses were used to evaluate patient characteristics (age, gender, body mass index, pre-injury Tegner activity level, activity at injury) and concomitant injuries on MRI (lateral meniscus, medial collateral ligament [MCL], isolated deep MCL, lateral collateral ligament, pivot-shift-type bone bruising, posteromedial tibial [PMT] bone bruising, medial femoral condyle bone bruising, lateral femoral condyle [LFC] impaction and a Segond fracture) associated with the presence of meniscal ramp lesions.

RESULTS

A total of 253 patients (52.2% males) with a mean age of 25.4 ± 7.1 years were included. The overall prevalence of meniscal ramp lesions was 39.5% (100/253). Univariate analyses showed that contact sports at ACL injury, pivot-shift-type bone bruising, PMT bone bruising, LFC impaction and the presence of a Segond fracture increased the odds of having a meniscal ramp lesion. Stepwise forward multiple logistic regression analysis revealed that the presence of a meniscal ramp lesion was associated with contact sports at ACL injury [odds ratio (OR) 2.50; 95% confidence intervals (CI) 1.32-4.72; P = 0.005], pivot-shift-type bone bruising (OR 1.29; 95% CI 1.01-1.67; P = 0.04), PMT bone bruising (OR 4.62; 95% CI 2.61-8.19; P < 0.001) and the presence of a Segond fracture (OR 4.38; 95% CI 1.40-13.68; P = 0.001).

CONCLUSION

The overall prevalence of meniscal ramp lesions in patients with ACL injuries was high (39.5%). Contact sports at ACL injury, pivot-shift-type bone bruising, PMT bone bruising and the presence of a Segond fracture on MRI were associated with meniscal ramp lesions. Given their high prevalence, meniscal ramp lesions should be systematically searched for on MRI in patients with ACL injuries. Knowledge of the factors associated with meniscal ramp lesions may facilitate their diagnosis, raising surgeons' and radiologists' suspicion of these tears.

LEVEL OF EVIDENCE

III.

Good results after treatment of RAMP lesions in association with ACL reconstruction: a systematic review

PURPOSE

This study aimed to systematically evaluate the clinical, functional, and radiological outcomes, complications, and rate of return to sports among patients with RAMP lesion of the medial meniscus encountered during anterior cruciate ligament (ACL) reconstruction.

METHODS

A systematic review was conducted based on the PRISMA guidelines. Two independent reviewers searched the PubMed, Scopus, Embase, and Cochrane Library databases using the terms "ACL" or "anterior cruciate ligament," and "RAMP lesion." The outcome measures extracted from the studies were the Short Form-12 (SF-12) in its mental and physical component (MCS and PCS), Lysholm score, Subjective IKDC, Marx Score, WOMAC Score, Tegner, Radiological changes, complications, failures and/or revision surgery, and rate of return to sports.

RESULTS

The cohort of patients consisted of 1,243 participants with a mean age of 28.6 ± 2.6. The mean postoperative follow-up was 40.9 ± 6.3 months. A total of 1145 (92.1%) RAMP lesions were repaired with concomitant ACL reconstruction, while only 98 (7.9%) lesions were left untreated (or treated with abrasion only). The Lysholm score was used in 6 studies (in one only at final follow-up), with a significant improvement in all the studies (Lysholm_pre 60.03 ± 6.12; Lysholm_post 89.9 ± 5.0). Eight studies out of nine reported Subjective IKDC score, and a significant improvement was noted in all cases (IKDC_pre 56.2 ± 5.8. IKDC_post 84.9 ± 3.7). Of 18 (1.4%) complications reported, 15 (1.2%) were related to RAMP/ACL surgery, and of the remaining three (0.2%) two (0.2%) were hematomas and one (0.1%) a contralateral ACL lesion. Of the 106 (8.5%) revision surgeries required, 5 (0.4%) were in non-treated lesions [two (0.2%) ACL re-ruptures and three (0.2%) medial meniscus re-injury]. In treated patients, the revision occurred for the following reasons: 75 (6.0%) meniscectomy, 14 (1.1%) meniscal suture revisions, 11 (0.9%) ACL failures and one (0.1%) arthrolysis.

CONCLUSIONS

It is not yet clear if, in all cases of ACL reconstruction in which a medial meniscal RAMP lesion is encountered, the lesion needs to undergo surgical repair. Accordingly, it is recommended that in the repair of all unstable medial meniscal RAMP lesions during an ACL reconstruction in cases associated with a stable RAMP lesion, the surgeon may decide on repair based on the patient profile.

LEVEL OF EVIDENCE

Level IV.

Diagnostic Performance of Multi-Direction Adjusted Multi-Planar Reconstruction with Helical CT for Evaluating Continuity of the Anterior Cruciate Ligament

RATIONALE AND OBJECTIVES

To analyze the diagnostic performance of MDA-MPR with CT for evaluating ACL structural continuity.

METHODS

A total of 145 patients with highly suspected ACL injury admitted to our hospital between January 2016 and May 2021 were retrospectively enrolled. All patients had undergone examination with MRI, CT, and arthroscopy. Taking arthroscopy results as the gold standard, the diagnostic accuracy for identifying ACL rupture by MRI and MDA-MPR with CT were compared.

RESULTS

The receiver operator characteristic curves demonstrated that both MRI and MDA-MPR with CT performed well in the diagnosis of ACL tears. The sensitivities of MRI and MDA-MPR with CT for diagnosing complete ACL tears were 95.16% (59/62) and 90.32% (56/62), respectively. Their specificities in this regard were 77.11% (64/83) and 84.34% (70/83), respectively. MRI had a higher sensitivity but MDA-MPR with CT had a higher specificity for detecting complete ACL tears, and the differences were statistically significant (p <.05). The sensitivities of diagnosing partial ACL tears using MRI and MDA-MPR with CT were 78.79% (26/33) and 75.76% (25/33), respectively, while the specificities were 86.61% (97/112) and 90.18% (101/112), respectively. These differences were non-significant (p >.05).

CONCLUSION

MDA-MPR with CT has high diagnostic efficiency for ACL injuries, especially in the diagnosis of complete ACL tears.

Meniscal Ramp Repair: A 2-Portal Posteromedial Approach

The management of medial meniscus ramp lesions can be challenging. The current gold standard technique to repair these lesions is the transnotch view combined with a single instrumental posteromedial portal. However, it does not provide direct visualization of the ramp and does not allow for an anatomic repair. In this Technical Note, a new technique is described with 2 posteromedial portals: a posteromedial viewing portal and working portal. This 2-portal approach aims to improve visualization of the lesion and its repair, as well as allow for a technically easier repair.

Epidemiology of Combined Injuries of the Secondary Stabilizers in ACL-Deficient Knees: Medial Meniscal Ramp Lesion, Lateral Meniscus Root Tear, and ALL Tear: A Prospective Case Series of 602 Patients With ACL Tears From the SANTI Study Group

BACKGROUND

Medial meniscal ramp lesion (MMRL), lateral meniscus root tear (LMRT), and anterolateral ligament (ALL) tear are individual injuries that have been described in patients who have an anterior cruciate ligament (ACL) tear. However, the prevalence of these lesions and their combination has not been defined.

PURPOSES

To define the individual and combined prevalence of MMRL, LMRT, and ALL tears in a case series of patients undergoing ACL reconstruction and to identify the risk factors for combined injuries.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients aged >15 years undergoing primary ACL reconstruction between January 2019 and June 2021 were enrolled in the study. A preoperative ultrasound scan was performed to look for an ALL tear. The presence of MMRL and LMRT was determined during a standardized arthroscopy exploration. A multivariate logistic regression model was used to determine the individual effect of patient variables on the risk of associated single, dual, triad, or tetrad injuries (MMRL, LMRT, ALL, ACL), represented by an adjusted odds ratio.

RESULTS

The case series consisted of 602 patients who underwent primary ACL reconstruction. An isolated ACL injury was present in 147 patients (24%). A dual injury was detected in 34 patients (6%) who had ACL-MMRL, 16 (2.65%) who had ACL-LMRT, and 265 (44%) who had ACL-ALL. A triad injury was detected in 80 patients (13.28%) who had ACL-ALL-MMRL, 36 (6%) who had ACL-ALL-LMRT, and 3 (0.5%) who had ACL-MMRL-LMRT. A tetrad injury pattern was detected in 21 patients (3.5%). Multivariate analysis showed that the occurrence of tetrad injury was significantly lower in older patients (adjusted odds ratio by year, 0.93 [95% CI, 0.88-0.99]; P = .028). Identifying LMRT increased the likelihood of finding MMRL-ALL injuries by 2.11 times (95% CI, 1.09-3.12; P = .031).

CONCLUSION

Isolated ACL tear is less common than combined injuries, which are quite frequent. Younger age is a risk factor for combined injuries. The search for damaged secondary stabilizers of the knee must be meticulous and systematic, especially when 1 injured structure has already been diagnosed.

Short-Term Outcomes After Treatment of Isolated Hidden Meniscal Ramp Lesions

Background:

Ramp lesions are encountered in 16% to 24% of all anterior cruciate ligament (ACL) ruptures. However, isolated ramp lesions without a ruptured ACL have also been reported.

Purpose:

To evaluate outcomes after type 3 hidden ramp lesions without ACL rupture were treated with all-inside sutures passed through the standard anterior portal.

Study Design:

Case series, Level of evidence, 4.

Methods:

Included were 41 patients (26 female; 63.4%) with isolated type 3 ramp lesions who underwent surgery between January 2017 and January 2019. Patients with concomitant lateral meniscal injuries and revision meniscal surgeries were excluded. We retrospectively recorded patient age, sex, and body mass index (BMI), as well as follow-up periods, comorbidities, and postoperative and early midterm complications. The Lysholm, visual analog scale (VAS) for pain, and International Knee Documentation Committee (IKDC) scores were compared preoperatively to final follow-up. In addition, patients were classified as having either a sedentary or active lifestyle according to Sedentary Behavior Research Network (SBRN) criteria. The Shapiro-Wilk test was used to evaluate the normality of the data, and the Wilcoxon and Mann-Whitney U tests were used to compare preoperative and postoperative outcome scores. The Spearman test was employed to evaluate the correlation between patient variables.

Results:

The mean follow-up period was at 37.6 (range, 25-49) months. A total of 17 patients (41.46%) had a sedentary lifestyle based on SBRN criteria. All scores improved significantly from preoperatively to final follow-up (VAS, from 8.43 ± 1.53 to 2.34 ± 2.9; Lysholm, from 47.73 ± 17.02 to 85.37 ± 14.01; and IKDC, from 27.12 ± 14.81 to 85.32 ± 8.78; P < .001 for all). Although no significant relationship was established between patient activity level and postoperative Lysholm and IKDC scores, an inverse correlation was observed between BMI and Lysholm (r =–0.9906) and BMI and IKDC (r =–0.9402).

Conclusion:

Satisfactory postoperative clinical results were obtained in patients with type 3 ramp lesions not accompanied by ACL rupture who were treated with all-inside suturing through standard anterior portals.

Meniscal Ramp Lesions: What the Radiologist Needs to Know

Meniscal ramp lesions are a special type of injury that affects the periphery of the posterior horn of the medial meniscus (PHMM) and/or its meniscocapsular attachments. They are strongly associated with acute and chronic anterior cruciate ligament (ACL) tears. These lesions have gained much prominence in recent years, due to a significant increase in their diagnosis and their important biomechanical involvement in the knee. It is known that their presence in ACL-deficient knees is related to instability and if they are not repaired during ACL reconstruction, they can ultimately cause the failure of the graft. Since this type of injury is often underdiagnosed due to its localization at the "blind" point of arthroscopic vision, it is crucial to make an accurate preoperative diagnosis of them with MRI. The objective of this article is to review the recent literature regarding meniscal ramp lesions and to summarize the anatomical, biomechanical and fundamentally diagnostic aspects, emphasizing the radiological findings described until now.

Meniscal Ramp Lesions: Anatomy, Epidemiology, Diagnosis, and Treatment

Injuries to the medial meniscus meniscocapsular junction, also known as ramp lesions, are common in the setting of anterior cruciate ligament injuries with a prevalence of 9% to 42%. Anatomically, ramp lesions involve disruption of the posterior meniscocapsular junction and meniscotibial ligaments. Biomechanically, ramp lesions are associated with an increase in anterior tibial translation and internal and external tibial rotation in anterior cruciate ligament-deficient cadaveric knees. Magnetic resonance imaging is useful in evaluating the meniscocapsular junction. Irregularity or increased signal near the posterior meniscocapsular junction and/or signal change indicative of posterior medial tibial plateau edema can suggest these injuries are present before surgical intervention. The current benchmark for diagnosis is arthroscopic visualization of the posterior medial meniscocapsular junction viewed through the intercondylar notch. Once a ramp lesion is identified, stability should be assessed by arthroscopic probing to determine the degree of anterior displacement. Optimal treatment has been debated in the literature, especially for stable ramp lesions, although good outcomes have been shown with and without repair. Repair is warranted for those lesions that are unstable to probing. Unfortunately, only limited literature available to guide clinicians on the optimal rehabilitation for ramp lesions.

The accuracy of MRI for the diagnosis of ramp lesions

OBJECTIVES

To assess the diagnostic accuracy of MRI in diagnosing ramp lesions in patients with an acute lesion of the anterior cruciate ligament (ACL).

MATERIALS AND METHODS

All consecutive patients over 15 years of age who underwent surgical repair of the ACL at a single hospital between January and May 2019, with MRI data available, were included in this retrospective study, except patients who had previous knee surgery. The gold standard was arthroscopic evaluation. Two trained radiologists with 5 and 14 years of experience did a blinded review of the MRIs. The following pathological signs were studied: complete fluid filling between the capsule and the posterior horn of the medial meniscus, irregular appearance of the posterior wall of the medial meniscus, oedema of the capsule, fluid hyperintensity in contact with the medial meniscus and anterior subluxation of the medial meniscus. Logistic regressions in univariate then multivariate analysis were carried out and measures of diagnostic accuracy and interobserver agreement were calculated with R software (version 3.6).

RESULTS

Fifty-seven patients were included. Twelve had a ramp lesion diagnosed by arthroscopy (21%). Only complete fluid hyperintensity between the posterior horn of the medial meniscus and the capsule was significantly associated with ramp lesions (P value < 0.01). The diagnostic accuracy of this specific sign was moderate, with a specificity of 84%, sensitivity of 75%, PPV of 56%, NPV of 93% and a good level of inter-observer agreement (k = 0.79).

CONCLUSION

The complete fluid filling is the only significant pathological MRI sign for ramp lesions, with moderate accuracy.

Knee Injuries in the Elite American Football Player: A Descriptive Pictorial Imaging and Mechanism of Injury Review

ABSTRACT

Musculoskeletal injuries are common in American football, with an incidence ranging from approximately 10 to 35 per 1000 playing hours. Injuries occur more commonly in games than in practice. Although several studies have analyzed specific injury types in football, this review aims to describe the most common knee injuries sustained by American football players and to review the existing literature pertaining to the radiologic findings used in the diagnosis of these injuries.